We have developed a new tool to analyse galaxies in the eagle simulations as close as possible to observations. We investigated the evolution of their kinematic properties by means of the angular momentum proxy parameter, λRe, for galaxies with M⋆ ≥ 5 × 109 M⊙ in the RefL0100N1504 simulation up to redshift two (z = 2). Galaxies in the simulation show a wide variety of kinematic features, similiar to those found in integral-field spectroscopic studies. At z = 0 the distribution of galaxies in the λRe–ε plane is also in good agreement with results from observations. Scaling relations at z = 0 indicate that there is a critical mass, Mcrit /M⊙ = 1010.3, that divides two different regimes when we include the λRe parameter. The simulation shows that the distribution of galaxies in the λRe–ε plane evolves with time until z = 2 when galaxies are equally distributed in both λRe and ε. We studied the evolution of λRe with time and found that there is no connection between the angular momentum at z = 2 and z = 0. All systems reach their maximum λRe at z = 1 and then steadily lose angular momentum regardless of their merger history, except for the high star-forming systems that sustain that maximum value over time. The evolution of λRe in galaxies that have not experienced any merger in the last 10 Gyr can be explained by their level of gas accretion.
The connection between the Stellar Velocity Ellipsoid (SVE) and the dynamical evolution of galaxies has been a matter of debate in the last years and there is no clear consensus whether different heating agents (e.g. spiral arms, giant molecular clouds, bars and mergers) leave clear detectable signatures in the present day kinematics. Most of these results are based on a single and global SVE and have not taken into account that these agents do not necessarily equally affect all regions of the stellar disc.We study the 2D spatial distribution of the SVE across the stellar discs of Auriga galaxies, a set of high resolution magneto-hydrodynamical cosmological zoom-in simulations, to unveil the connection between local and global kinematic properties in the disc region. We find very similar, global, σz/σr = 0.80 ± 0.08 values for galaxies of different Hubble types. This shows that the global properties of the SVE at z=0 are not a good indicator of the heating and cooling events experienced by galaxies. We also find that similar σz/σr radial profiles are obtained through different combinations of σz and σr trends: at a local level, the vertical and radial components can evolve differently, leading to similar σz/σr profiles at z=0. By contrast, the 2D spatial distribution of the SVE varies a lot more from galaxy to galaxy. Present day features in the SVE spatial distribution may be associated with specific interactions such as fly-by encounters or the accretion of low mass satellites even in the cases when the global SVE is not affected. The stellar populations decomposition reveals that young stellar populations present colder and less isotropic SVEs and more complex 2D distributions than their older and hotter counterparts.
Yttria–alumina–silica (YAS) glass microspheres doped with Nd3+ ions were excited with a 532 nm continuous laser in order to study the dependency of the wavelength of the whispering gallery mode (WGM) peaks on the temperature of the sample. This was possible due to a previous calibration of the 808 nm and 890 nm emission bands of the Nd:YAS glass sample for different temperatures using the fluorescence intensity ratio (FIR) technique. A maximum sensitivity of 15 × 10−6 K−1 and a temperature resolution limit of 0.2 K were obtained for the microsphere sensor. Moreover, laser emission at 1064 nm was observed by continuous pumping at 532 nm, and a power threshold of 100 mW was determined. Upconversion emissions of Nd3+ were also studied by exciting the sample at 808 nm.
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